I. Field of the Invention
The present invention relates generally to the field of an improved means for pulling lengths of communication and electrical cable through a buried or underground conduit, especially in sizes that exceed the normal strength of a mechanic's pull and the inertia that comes from an irregular pull.
Typically, cable is pulled through a conduit by using a machine of some sort to pull the wire or cable through the electrical conduit. Inasmuch as cable comes in various sizes, a machine which is built to the standards for pulling a particular size of cable and a machine which is portable, so that the working person may move it from job site to job site, has many advantages. Obviously, portability of the equipment makes for efficiency of time and effort. On long lengths of cable which are to be pulled through a long conduit, it is obviously necessary to have some sort of a machine with mechanical advantage and one which will effect the pull of the cable at a proper angle with respect to the longitudinal axis of the exit end of the conduit.
II. Description of the Related Art
There are many ways to pull cable through conduit. Probably the most basic is to feed a line through the conduit by known means, then tie the line to the free end of the cable to be pulled and subsequently haul on the line, by hand, thereby pulling the cable through the conduit. However, anyone who has tried this particular procedure will know that over a relatively short length of conduit, the friction between the conduit and the cable becomes such that it is nearly physically impossible to effectively pull a cable through any substantial length of conduit.
The prior art knows of more practical machines for pulling cable through conduit. For instance, U.S. Pat. No. 2,655,653 granted to Chauvin discloses a powered cable pulling machine that is mounted on a trailer and is able to pull a cable at a proper angle by adjusting the height of the trailer tongue.
In U.S. Pat. No. 4,497,470 by Carter et al, an electrically powered dolly mounted cable pulling machine is shown, however, this particular machine has limited capabilities for pulling the cable at a correct angle.
The patents to Giroux, namely, U.S. Pat. Nos. 4,695,038 and 4,836,503 disclose trailer mounted cable pulling machines wherein each machine has a plurality of frame mounted, hydraulically driven pinch wheels to achieve speed and torque in pulling long lengths of cable without damaging the cable.
A non-powered cable pulling machine is shown in U.S. Pat. No. 5,653,293 to Ellis and discloses a cable puller that, while portable, requires a prime mover to supply hydraulic power to operate the machine.